Little is known about the mechanisms that allow the brain (i.e., the cortex) to selectively improve the neural representations of behaviorally important stimuli while ignoring irrelevant stimuli. Some current neuroscience research indicates that learning is related to the ability of the brain to form new networks of nerve connections, a phenomenon termed herein as "brain plasticity". The formation of new nerve connections is also referred to herein as brain reorganization. Diffuse neuromodulatory systems may facilitate cortical plasticity by acting as a teacher to mark important stimuli. That is, it is believed that learning may be related to many factors such as, for example, the "behavioral importance" collectively attached by several brain regions in weighing or processing the subject matter to be learned (i.e., the incoming stimuli or activity). In addition, it is believed that learning is also related to how much attention the learner focuses on the incoming stimuli. Thus, it is believed that learners generally must put significant effort into learning and memorizing processes. It is believed that some types of learning disability may be related to an impaired ability to focus attention and/or attach behavioral importance on the incoming stimuli or activity.
The learning and memorizing process can be further affected by injury to the brain caused, for example, by a stroke. Stroke patients often incur lost brain functions such as speech, accurate hearing and movement. However, it has been observed that stroke patients often lack the will to participate vigorously in rehabilitation programs for recovering or relearning brain functions lost due to the stroke. Further, because the stroke damages brain cells, brain resources are more limited or may even have a diminished ability to generate "behavioral importance", which may contribute to the commonly slow recovery process.
Accordingly, there is a need for a learning system that stimulates brain plasticity with reduced dependence on both behavior importance and the degree of attention on the incoming stimuli.